diff --git a/docs/markdown/Reference-manual.md b/docs/markdown/Reference-manual.md index e6aa9d330..4be06c4a2 100644 --- a/docs/markdown/Reference-manual.md +++ b/docs/markdown/Reference-manual.md @@ -316,6 +316,13 @@ otherwise. This function supports the following keyword arguments: You can also specify multiple restrictions by passing a list to this keyword argument, such as: `['>=3.14.0', '<=4.1.0']`. +If dependency_name is '', the dependency is always not found. So with +`required: false`, this always returns a dependency object for which the +`found()` method returns `false`, and which can be passed like any other +dependency to the `dependencies:` keyword argument of a `build_target`. This +can be used to implement a dependency which is sometimes not required e.g. in +some branches of a conditional. + The returned object also has methods that are documented in the [object methods section](#dependency-object) below. @@ -436,10 +443,7 @@ be passed to [shared and static libraries](#library). The list of `sources`, `objects`, and `dependencies` is always flattened, which means you can freely nest and add lists while -creating the final list. As a corollary, the best way to handle a -'disabled dependency' is by assigning an empty list `[]` to it and -passing it like any other dependency to the `dependencies:` keyword -argument. +creating the final list. The returned object also has methods that are documented in the [object methods section](#build-target-object) below. diff --git a/mesonbuild/interpreter.py b/mesonbuild/interpreter.py index ff93feb45..86d25eae0 100644 --- a/mesonbuild/interpreter.py +++ b/mesonbuild/interpreter.py @@ -2146,6 +2146,12 @@ to directly access options of other subprojects.''') def func_dependency(self, node, args, kwargs): self.validate_arguments(args, 1, [str]) name = args[0] + + if name == '': + if kwargs.get('required', True): + raise InvalidArguments('Dependency is both required and not-found') + return DependencyHolder(Dependency('not-found', {})) + if '<' in name or '>' in name or '=' in name: raise InvalidArguments('Characters <, > and = are forbidden in dependency names. To specify' 'version\n requirements use the \'version\' keyword argument instead.') diff --git a/test cases/common/171 not-found dependency/meson.build b/test cases/common/171 not-found dependency/meson.build new file mode 100644 index 000000000..7d92f5ae6 --- /dev/null +++ b/test cases/common/171 not-found dependency/meson.build @@ -0,0 +1,8 @@ +project('dep-test') + +dep = dependency('', required:false) +if dep.found() + error('not-found dependency was found') +endif + +assert(dep.type_name() == 'not-found', 'dependency should be of type "not-found" not ' + dep.type_name()) diff --git a/test cases/failing/67 dependency not-found and required/meson.build b/test cases/failing/67 dependency not-found and required/meson.build new file mode 100644 index 000000000..1ce574738 --- /dev/null +++ b/test cases/failing/67 dependency not-found and required/meson.build @@ -0,0 +1,2 @@ +project('dep-test') +dep = dependency('', required:true)